Tube spacer and support



Feb. 4, 1947. J, ANDREW, JR v 2,415,068

TUBE SPACER AND SUPPORT Filed July 13, 1945 2 Sheets-Sheet 1 amlmwlwu Tig. 3

' INVENTOR. James DAndreugJr:

BY v

VA ITORNE Y L Feb. 4, 1947.

J. D. ANDREW. JR

TUBE SPACER AND SUPPORT Filed July 15. 1943 2 Sheets-Sheet 2 r as r 132f 90 I06 I;

' I28 Ho Fig. 5

A mwshron James D. Andrew, J1."

y i n A TI'ORNE Y atented Feb 1947 UNITED STATES PATENT OFFlCE Tunasracna Am) surron'r James D. Andrew, In, Essex Fells, N. 3., asslgnor toThe Babcock & Wilcox Company, Rock- Ieigh, N. 1., a corporation of NewJersey Application July 1a, 1943, Serial No. 494,5

The invention herein disclosed relates to a tube spacer construction formaintaining the tubes of a bank of tubes in predetermined spacedrelation transversely of their lengths. The invention is applicable tothe fluid carrying tubes 13 Claims. (cl. 122'4'i8) In accordance withthis invention it is also an object t'outilize a. material or materialssufliciently resistant to 'the temperatures to be encountered as 'toafford a construction relatively permanent in character.

of heat exchangers generally but is especially' advantageous whenapplied to the tubes of a heat exchanger wherein relatively long'lengthsof tubes are arrangedupright and are swept by' heating gases ofrelatively high temperatures.

It is known that in convection heated apparatus of the character hereindescribed the spacing of the tubes transversely of their lengths has animportant bearing on the rate of heat transferand, with other conditionsremaining constant, a closer spacing of the tubes results in a higherrate of heat transfer. When tube spacings are 'made small, any variationin the spacing between individual tubes of the bank alters the areaavailable for gas flow between tubes, and because of the normally closespacing the change in gas flow area is a high percentage of the intendedarea, and the resulting gas mass flow becomes appreciably higher orlower depending on the' direction of change.

Such displacements of the tubes may result from overheatingof the tubemetal causing distortion due to the high temperatures of the heatinggases in relation to temperatures of the fluid withinthe tubes. Sincethe tubes of An additional object is to provide a spacer support capableof being manufactured and installed simultaneously, thereby contributingto savings in labor and expense, and by forming an essentiallymonolithic structure enabling a predetermined, spacing of the tubes tobe maintained.

The foregoing objects and advantages, as well as others will be morefully understood from the description to follow, particularly when readin conjunction with the accompanying drawings, in which:

Fig. 1 is a sectional side elevation of a boiler unit illustrating anembodiment of my invention as applied to the superheater thereof;

Fig. 2 is a sectional plan of the boiler unit shown in Fig. 1,- takenalong line 2-4;

themselves are unable to resist this tendency to become distorted, ithas been customaryto employ spacer elements ofone description or anotherin an attempt to maintain the spacings at their intended normal values,but such means as heretofore used have been inadequate in that they donot provide a sufficiently rigid lateral support to the tubes in everydirection, nor do they afford an especially durable separator meanscapable of withstanding the high temperatures of the heating gases overreasonably long periods before requiring replacement.

Spacer elements for the tubes of superheaters, for example, have usuallybeen made of metal, andbecause of the high temperatures involved, suchelements have been formed of various alloys whose compositions for themost part Fig. 3 is a fragmentary enlargement of parts shown in Fig, 1;

Fig. 4 is a plan view, partly broken away, of partsshown in Fig. 3; Fig.5 is a sectional. side elevation of a boiler unit showing an applicationof my invention in modified form, and

Fig. 6 is an enlarged fragmentary plan section of partsshown in Fig. 5.

In detail and referring particularly to Figs. 1 and 2, the boiler unitas shown is of the integral-furnace type wherein the boiler furnace orcombustion chamber i0 is located to one side of the boiler heatingsurface comprising groups of upright boiler tubes i2, i4 and I6 whichare connected to the upper and lower boiler drums require metals'whichare not only. expensive, but

18 and 20. The disposition of boiler heating surface in relation to theboiler furnace is generally similar to the arrangement disclosed in U.S. Patent to E. G. Bailey et a1. 1,999,984, granted April 30, 1935. Thefurnace is suitably fired from one end as indicated in Fig. 2, utilizingburners 22 'of atype selected for the character of fuel or fuels to beburned.

The hot gases of combustion are discharged from the furnace chamberthrough the gas outlet provided between one end of the inclineddeflector bailie 26-and the adjacent wall 28 of the setting, thegasesbeing directed over the groups of boiler tubes l2, l4 and it through aplurality of transverse heating gas passes 30, 32 and 34 arranged in ahorizontal series adiacentthe side wall ,36 of the setting,such-passes.being principallydei'lned by :the transverse bailie walls 38and 40, and the longitudinal baflle wall 42, in combination withadjacent walls of the setting. The

spent heatingga'ses leave the setting through the gas outletconveniently located at the bottom of the final gas pass 34.

In their course through the first gas pass 30 the hot gases ofcombustion are directed over the tubes of a superheater 46 wherein thesuperheater tubes 48 are formed as U-shaped loops and are arrangedupright with the closed ends of the loops uppermost. A sectiontransversely of the superheater tube bank, as illustrated in Fig. 2,shows the tube lengths as being arranged in bundles and being spacedapart in successive rows extending transversely of the direction of gasflow and, in addition, in successive rows paralleling the direction ofgas flow. The superheater tubes have their ends connected to bottomheaders 58, 52 and 54, one group of tubes connecting the inlet header 58with an intermediate header 52, and the remaining group of tubesconnecting the intermediate header 52 with, the outlet header 54,thereby causing steam to pass through the two groups of superheatertubes in succession. The inlet and outlet headers 50 and 54 may be madeseparate, or may be formed as separate sections of the same header, thesaturated steam being conducted to the inlet header or section 50through connections 56 leading-from the upper steam and water drum [8.The headers er level intermediate the intended thickness of 50, 52, 54are cradled in longitudinally spaced cantilever beams 58 which are fixedto the lower boiler drum 20 thereby supporting the superheater entirelyfrom below. tory 60 above the headers serves as a protection for thesuperheater tube connections and the header supports 58.

The preferred means for maintaining the superheater tubes 48 in apredetermined spaced 'relation is essentially monolithic and formed as Alayer of refracthe finished plate as shown. Some or all of the wires maybe welded to certain tubesof the bank as indicated at 88 as a means ofresisting any tendency for the completed spacer to shift along thetubes.

It is desirable to make certain that the tubes 48 are properly spacedand in alignment before placing the material 64 within the form, andpreferably to provide some temporary spacer means (not shown) designedto remain in place until the material 64 has fully hardened. Thematerial 64 in its initially fluid or plastic state is poured or rammedinto the form or mold which has been provided, to completely fill thespaces between and around the tubes 48 and, being somewhat cementitiousin character, will upon hardening form a solid substantially monolithicand self-sustaining structure capable of maintaining its shape under allservice conditions, the

hardened materialconforming closely to the contours of the tubes, andadhering to a degree to their surfaces, to preserve the intended tubethe application of heat and retains its hardness I and strength up toits limiting temperature of 2600 F., in addition to having low expansionand shrinkage values and providing adequate resistment. Each plate 62for each leg of the tube bank is preferablydi vided at 68 into separatesections 62a and 62b thus providing a separate section for each leg foreach pass of the steam through the superheater, a section 62a beingprovided for each leg of tubes conducting steam at a-relatively lowtemperature from the saturated steam inlet header 58 to. theintermediate header 52, and a section 62b being provided for each le oftubes conducting steam at a higher temperature from intermediate header52 .to the superheated steam outlet header 54.

The installation of the tube spacer 62 is facilitated by constructing atemporary form about the tubes 48 at the desired location, as indicatedby dotted lines in Fig. 3. *Such a form. of wood for example, mayconsist of a pair of beam members 18 extending across the direction ofgas flow,

boards 16 and "completing the temporary structure.

The wires, or rods 66 may then be placed between thetubes at the desiredintervals, either and variation in spacings of the tubes.

ance to abrasion.

In View of the inclination of the tubes '48, the tendency for the tubebank to rotate about its lower support 58 is opposed by angles 82secured as by U-bolts 84 to adjacent boiler tubes 86.

It has been found that a single plate 62 for each leg of'the superheatertube bank.46 is adequate for maintaining tube spacing and alignmentwhere 'previously a plurality of metallic spacers had been required. Themonolithic type of spacer provides a substantially permanently rigidassembly whereas with the metallic spacers formerly employed, amultiplicity of parts was required, involving numerous separateassemblies, and resulting in an overall assembly of the bank which wassubject to distortion of its shape in service and consequentmisalignment Moreover, the monolithic type of spacer 62 is in itself,highly refractory to the hot combustion gases independent of anycooling effect due to its thermal engagement with the tube walls. In thecase of metallic spacers, the original thermal contact with the tubes isgenerally incomplete and ordinarily cannot be maintained, so thatregardless of the metal employed, whether cast iron or a temperatureresistant alloy,; the spacers are apt to be burned away with a,resulting variation in tube spacings and an impairment in the rate ofheat transfer.

In the modification according to Figs. 5 and 6, the boiler unit is of atype wherein the major portion of the boiler heating surface comprisesbanks of tubes 88 and 90 connected to upper and lower boiler drums 92and 94 and laterally adjoining a boiler furnace or combustion chamber 06fired by burners 08 suitable for the fuel or fuels to be burned.

A superheater I is positioned between the banks of boiler tubes 88 and'90, being screened in part from the radiant heat of the combustion.chamber by the bank of boiler tubes 90. Saturated steam is conductedfrom the upper boiler drum 92 by means of tubes I02 to. the inletsuperheater header I04 from which it passes through vertically extendingtubes I06 of a first section of the superheater to an intermediateheader I08; thence through connections IIO to a desuperheater unit (notshown) within the lower drum 94; thence through connections Hz to anintermediate header H4; and then through vertically extending tubes II6of asecond superheatersection to the superheater outlet header H8.

The hot gases of combustion leaving the'fur nace chamber 96 sweep acrossthe entire exposed lengths of boiler tubes 90 and immediately thereafterengage the banks of superheater tubes H6 and I00 in succession,whereupon the flow of gases is continued throughout'the boiler bank 88in a plurality of longitudinal passes H9, I20 and ma to the gas outletI24.

A monolithic form of spacer plate I 26 is employed for each of the banksor bundles of superheater tubes I06 and IIS, similar in construction andmaterial to the spacer means 62, and

for this reason such details need not be repeated.

- viating the use of the usualoverhead metallic suspensionmembers whichbecause of the temperature zone in which located would require the useof heat resistant alloys difficult to obtain,

the weight of the superheater being carried by a plurality of suitablysupported transverse beams I20 on which rest the-superheater headersI04, I108, ill and H8.

The tubes I06 andIIIi of both superheaterv sections are in multiple loopformation, so that each tube I06 or I I6 provides a plurality of passesacross the flow of heating gases. Asseen in Fig. 6, the spacing of,tubes I06 in rows extending longitudinally of the upper drum I8 isone-half the spacing of the superheater tubes H6, and of the boilerscreen tubes 90, in similarly arranged rows. All of the superheatertubes H6 may therefore be'extended upwardly to a level where their upperloop ends are between the horizontally extending .portions I30 of theboiler screen tubes 90 which thus serve to prevent excessive relativemovement laterally between the tubes H0 at their ends. Due to the closerspacing of tubes I06 in the other section of the superheater, only halfof these, could be conveniently extended upwardly into thespaces betweenthe horizontal boiler tube portions I30, and consequently, inpreference, a monolithic bafile structure I32 is provided adjacentthe'roof of the set-. ting, and the upper loop ends of tubes I 06'extended into the lower wall thereof, desirably through individualopenings therein, whereby excessive relative movement of such tube endsis similarly prevented. The guiding of tubes I06 and H0 at their upperloop ends, as described, permits expansion and contraction of thebottom-supported tube lengths with minimum distortion, and inconjunction with the rigid monolithic spacer I26 at an intermediatelocation, enables longentube loops to be used than if the upper loopends were left entirely free and unrestricted as to relative lateralmovement. For example, but without indicating specific limitations ofthe invention, in the form of Fig. 1 where the upper loop ends are leftfree, the height of the loops above the layer of refractory B0 isapproximately one hundred three times the diameter of the tubes, whereasin the form of Fi .5 where the .upper tube ends are guided, the heightof the loops above the floor I34 of the setting may be approximately onehundredtwenty-nine times the diameter of the tubes, the increase inratio, 'ofloop length to tube diameter thus being approximatelytwenty-five per cent.

The invention as herein disclosed in accordance 25. with the provisionsof the statutes will be understood by persons skilled in the art to beapplicable in arrangements other than those specifically described, andto include features which may be used to advantage without acorresponding use of other features, within the scope of the appendedclaims.

I claim:

1. In combination with a bundle of closely spaced superheater tubesarranged upright for transverse flow of heating gases thereover in asingle gas flow heating pass, said tubes being arranged in rowsparalleling said heating gas flow With several of said tubes in each ofsaid .rows, a

header at thelower ends of said tubes to which 40 said tubes areconnected for sustaining the weight of said tubes and for maintainingthe lowermost extremities of individual tubes in spaced relationtransversely of said bundle,

means for maintaining said .tubes in predetermined spaced relationthroughout other portions of their lengths comprising a slab of hardenedplastic heat resistant material installed between and around said tubestransversely of said. bundle at a location intermediate the height ofsaid bundle, and means associated with said slab and cooperating solelywith said tubes for maintaining said spacer slab substantially fixed inposition longitudinally of said tubes.

2. In combination with serially connected bundles of superheater tubesadapted to be contacted successively by heating gases flowingtransversely thereover, the tube lengths throughout each bundle beingarranged upright and being spaced apart both in the direction .of gasflow and in a direction transversely thereto, said tube lengths beingarranged in rowsparalleling said heating gas flow with several of saidtube lengths in each of said rows, means for supporting the weight ofsaid tubes'entirely from below, and

plate-like members predominantly monolithic and non-metallic eachextending across the tube lengths of one of said bundles for separatelysupporting the tube lengths of each bundle laterally to maintainpredetermined spacings between tube 7 lengths in said bundles, each saidspacing and supporting member engaging only the tube lengths of one. ofsaid bundles and being sustained solely thereby. i

3. In combination with a bank of inverted U- shaped superheater tubeshaving the major pormeans for supporting said headers and thereby theentire weight of said superheater tubes, and monolithic means disposedtransversely of at least said bundle first contacted by said gases forrigidly supporting the tube lengths of said bundle against lateraldisplacement, whereby the spacing between the tube lengths of saidbundle is maintained constant, said monolithic spacer lengths of saidbundle and having its weight supported wholly thereby, said bundlecomprising tube lengths arranged in a plurality of rows paralleling theflow of said gases with a'plurality of tube lengths disposed in each ofsaid rows.

4. In combination with a bankof inverted U- shaped superheater tubeshaving the major portions of their lengths. straight and formingserially connected spaced bundles of tube lengths adapted to'becontacted successively by heating gases flowing transversely thereof,each bundle comprising tube lengths arranged in a'plurality of rowsparalleling the flow of. said gases with a plurality oi tube lengthsdisposed in each or said rows, headers to ,which the lower ends of saidtubes are connected, means for supporting said headers and thereby theentire weight of said superheated tubes, and monolithic members eachdisposed transversely of one of said bundles for rigidly, supporting thetube lengths of each bundle separately against lateral displacement,whereby the spacing between tube lengths in a given bundle is maintainedconstant without interferlngwith the movement of one bundle relative toanother, each said monolithic spacer and supportingmember for eachbundle having its weight supported wholly by the bundle of tubes engagedthereby.

5. In combination, a bank of upwardly extending superheater tubesadapted to be swept by heating gases flowing transversely thereover to aand supporting means engaging only the tube nected by loops attheiruppere'nds and arifg for transverse flow of high temperatureheating gases thereover, the straight length portions in each of saidgroups being'arranged in rows paralleling said heating gas flow withseveral of said portions in each of said rows, means forsupporting theweight of said tube bank entirely from below, and means for rigidlysupporting said tubes laterally at a location intermediate their heightsto maintain constant relative spacings between the straight lengthportions in a selected group, said last named means comprising apredominantly monolithic and nonmetallic plate-like member extendingtransversely of the tube portions of' said group and being whollysupportedthereby, said member engaging only the tube portions in saidgroup and being in close fitting relation to all said tube portions insaid group.

7. In a'superheater having tubes arranged in bundles forming successiveportions of the flow path for the fluid being heated, each bundlecomprising straight length tube portions arranged upright in transverserelation to the flow of high temperature heating gases thereover in asingle gas flow heating pass, said straight length portions beingdisposed in closely spaced rows paralleling the direction of heating gasflow with a plurality of said portions in closely spaced relation ineach of said rows, means for supporting the weight of at least one ofsaid bundles of superheater tubes entirely from one end includingstationary header means to which the corresponding ends of the tubes ofsaid bundle are connected and the tubes thereby held in fixed lateralrelation only at said end of support, and means for maintaining otherportions of the tubes of said end supported bundle in predeterminedspaced relation in all directions laterally throughout said bundlecomprising a substantially monolithic and gas outlet adjacent the upperportion of said bank, said tubes including vertically extending straightlengthportions connected at their ends by return bendsto forma.succession of continuous tube lengths in looped formation eachparalleling the direction of heating gas flow, headers below the levelof said bank to which the ends of sa-idlooped tube lengths areconnected, means a for supporting said headers'and thereby the entireweight of said superheater tubes, a rigid plate-like structure arrangedtransversely of said straight tube length portions at a levelintermediate the height of said bank for maintaining the spacing of saidtube length portions constant, said structure being predominantlymonolithic and beingsustained solely by tub lengths enga'ged thereby,said structure being disposed at a level below said gas outlet andarranged to deflect a portion of said heating gases downwardly to offsetthe tendency for some of said gases to bypass the lower portions ofsaid'superheater non-metallic heat resistant plate-like member extendingtransversely of the straight length tube portions at a locationintermediate the heightof said single heating gas pass, said membersembracing substantially all straight length tube portions in all ofsaidrows in closely fitting relation to the walls'thereof, said memberembracing only the tubes of a single bundle and havin its I weightsupported wholly thereby.

8. In a superheater having tubes arranged in serially connected bundlesfor successive flow of high temperature heating gases thereover in asingle transverse pass, each bundle comprising straight length tubeportionsiarranged upright and disposed in closely spaced relation inrows paralleling the direction of heating gas flow with a plurality ofsaid portions in closely spaced relation in each of said rows, means forsupp rting the weight of said superheater tubes entirely from one endincluding stationary header means to which said tubes are connected andthereby held in fixed lateral relation only at said end of support, saidheader means including an inlet, an intermediate, and an outlet headersection, said tubes being connected to said sections to provide aprogressive fluid flow path from 'said inlet to said outlet section inaplurality of passes relative to vthe flow of said heating gases, one ofsaid bundleshavlng all of its tubes connected to said intermediateheader section, a second bundle comprising a first group oi tubesconnected to said inlet header section and a second group of tubesconnected to said outlet header section, and a, heat resistantplate-like member predominantly monolithic disposed transversely of thetubes of at least said second bundle at a lofitting relation to the tubewalls, said member embracing only the tubes of a single bundle, themember for said second bundle being divided into separaterelativelymovable portionsfor said first and second groups of tubes.

9. In combination, a heat exchanger formed of tube lengths arrangeduprightv in separate bundles and connected to provide a progressive flowpath for the fluidbeing heated, said bundles being arranged insuccession relative-to the flow of high temperature heating gasesthereover in a single transverse pass, said tube lengths being disposedin a plurality of closely spaced rows paralleling the direction ofheating gas flow with at'least several of said lengths in closely spacedrelation in each of said rows, means for fixin the positions of saidtube lengths at one'end only of each bundle thereby leaving otherportions of said tube lengths toward the opposite end of each bundlefree to move in response to temperatur variations, refractory plate-likemembers of substan tially monolithic formation each arrangedtransversely of the tube lengths of one of said bundles and forming aseparate rigid support and spacer means for the tube lengths of saidbundle in all directions laterally throughout said bundle, each saidmember being disposed at a level intermediate the height of said tubelengths in said single heating gas pass and being sustained solely bythe tube lengths engaged thereby.

10. In combination with a bundle of closely spaced superheater tubelengths arranged upright for transverse flow of heating gases thereoverin a single gas flow heating pass, said tube lengths being arranged inrows paralleling said heating gas flow with several of said lengths ineachof said rows, means for sustaining the weight of said bundle fromone end only and for maintaining the extremities of individual tubelengths at said end in spaced relation transversely of said bundle, aslab of plastic heat resistant material hardened in place between andaround said tube lengths transversely of said bundle ata locationintermediate the height of said bundle, and means secured to tubelengths embraced by said slab for maintaining said slab in apredetermined position longitudinally of said bundle, said slabconstituting the sole means other than said first named means formaintaining said tube lengths in predetermined spaced relationthroughout their lengths.

11. In combination with a bank 01' inverted U- shaped superheater tubeshaving the major portions of their lengths straight and taming seriallyconnected bundles of tube lengths .adapted to be contactedsuccessivelyby heating gases flowing transversely thereover, each bundle comprisingtube lengths arrangedin a plurality of rows paralleling the flow of saidgases with a plurality of said tube lengths disposed in each of saidrows, headers to which the lower ends of said tubes are connectedincluding inlet and outlet headers between which steam entering saidinlet headeris caused to flow through said tubes to said outlet headerin a plurality of passes relative to the flow of said heating gases,means for supporting said headers and thereby the entire weight of saidsuperheater tubes, and separateplate-like means disposed transversely ofthe tube lengths of each of said bundles for maintaining the spacingbetween said tube lengths constant without interfering with the movementof one bundle relative to another, said tube spacing means for any oneof said bundles being divided into relatively movable sections at alocation corresponding-to the division between a plurality of said steamflow passes, each of said. sections being predominantly monolithic andbeing supported wholly by the tube' lengths with which it is associated.

* 12. In combination with a bundle of closely spaced superheater tubelengths arranged upright for transverse flow of heating gases thereoverin a single gas flow heating pass, said tube lengths being arranged inrows paralleling said heating gas flow with several of said lengths ineach of said rows, means for sustaining the weight of said bundle fromone endpnly and for, maintainin the extremities of individual tubelengths at said end in spaced relation transversely of said bundle, anda slab of plastic heat resistant material hardened in plac between andaround said tube lengths transversely ofsaid bundle at a locationintermediate the height of 'said bundle, said slab being supportedsolely by the tubelengths engaged thereby and constituting I the solemeans other than said first named means for maintaining said tub lengthsin predetermined laterally spaced relation.

13. In a heat exchanger having fluid conducting tubes arranged inserially connected bundles for successive flow of high temperatureheating gases thereover in a single transverse pass, each bundlecomprising substantially straight tube lengths arranged upright anddisposed in closely, spaced relation in rows paralleling'the directionof heating gas flow with a plurality of said tube lengths in closelyspaced relation in each of said rows, means for supporting the weight ofsaid tubes entirely from one end including header means havingconnections with said tubes arranged to provide therethrough aprogressive fluid flow path divided into a plurality of fluid flowpasses relative to the flow of said heating is associated.

JAMEs D. ANDREW, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name 1 Date 1,948,939 Noack Feb. 27, 19342,326,513 Bailey, et a1 Aug.,10,-1943 2,184,626 Smith, et a1 Dec. -26,1939 1,748,113 Danks, et al. .i,' Feb. 25, 1930 9 Emmet Jan, 14,19411,289,979 Warriner Dec. 31, 1918 1,921,049 Tompkins Aug. 8, 19331,999,984 Bailey, et al Apr. at, 1935 2,158,508 Kuhner "-1 May 1 ,1939

